Clear pending signal when configuring timer

src/os/posix/ostimer.c

@@ -325,6 +325,7 @@ int32 OS_TimeBaseCreate_Impl(uint32 timer_id)
     int    status;
     int    i;
     struct sigevent   evp;
+    struct timespec ts;
     OS_impl_timebase_internal_record_t *local;
     OS_common_record_t *global;
     OS_U32ValueWrapper_t arg;
@@ -403,6 +404,34 @@ int32 OS_TimeBaseCreate_Impl(uint32 timer_id)
             sigemptyset(&local->sigset);
             sigaddset(&local->sigset, local->assigned_signal);
 
+            /*
+             * Ensure that the chosen signal is NOT already pending.
+             *
+             * Perform a "sigtimedwait" with a zero timeout to poll the
+             * status of the selected signal.  RT signals are also queued,
+             * so this needs to be called in a loop to until sigtimedwait()
+             * returns an error.
+             *
+             * The max number of signals that can be queued is available
+             * via sysconf() as the _SC_SIGQUEUE_MAX value.
+             *
+             * The output is irrelevant here; the objective is to just ensure
+             * that the signal is not already pending.
+             */
+            i = sysconf( _SC_SIGQUEUE_MAX);
+            do
+            {
+                ts.tv_sec = 0;
+                ts.tv_nsec = 0;
+                if (sigtimedwait(&local->sigset, NULL, &ts) < 0)
+                {
+                    /* signal is NOT pending */
+                    break;
+                }
+                --i;
+            }
+            while(i > 0);
+
             /*
             **  Initialize the sigevent structures for the handler.
             */

src/unit-tests/ostimer-test/ut_ostimer_test.c

@@ -79,10 +79,8 @@ void UT_os_timercallback(uint32 timerId)
 
         OS_GetLocalTime(&endTime);
 
-        if (endTime.seconds == currTime.seconds)
-            currIntervalTime = endTime.microsecs - currTime.microsecs;
-        else
-            currIntervalTime = endTime.microsecs + (1000000 - currTime.microsecs);
+        currIntervalTime = 1000000 * (endTime.seconds - currTime.seconds) +
+            endTime.microsecs - currTime.microsecs;
 
         if (currIntervalTime >= prevIntervalTime)
             deltaTime = currIntervalTime - prevIntervalTime;
@@ -102,18 +100,12 @@ void UT_os_timercallback(uint32 timerId)
             res = -1;
 
         loopCnt++;
+        currTime = endTime;
+        prevIntervalTime = currIntervalTime;
 
-        if (loopCnt < g_cbLoopCntMax)
-        {
-            currTime = endTime;
-            prevIntervalTime = currIntervalTime;
-        }
-        else
+        if (loopCnt == g_cbLoopCntMax)
         {
             g_status = (res == 0) ? 1 : -1;
-
-            /* slow the timer down so the main test thread can continue */
-            res = OS_TimerSet(g_timerId, 1000, 500000);
         }
     }
 }